Lotus japonicus seeds were scarified, subjected to water absorption for 30 min, and sown in quartz sand. The seeds were then germinated at 25°C and grown in a plant growth chamber with daily cycle of 16 hours of light at 25°C and 8 hours of dark at 23°C (BioTRON; Nippon Medical & Chemical Instruments Co., Ltd.). The plants were fertilized with 1000-fold diluted Hyponex® solution (N:P:K = 6:10:5) once a week. One-month-old L. japonicus were used in extracting plant hormones.